In the manufacture of electronic circuits on semiconductor wafers or substrates, many processes use a coating of photoresist on the substrate to define the circuit to be etched or deposited on the substrate surface. The process of depositing the photoresist coating is often done on a spin-apply tool wherein the substrate is spun on a spin chuck while photoresist is applied.
Spinning the substrate while the photoresist is applied results in atomized liquid flying off the substrate and the chuck. Thus, the spinning process is usually done inside some sort of enclosure having a basin to catch the liquid. The atomized liquid may form a cloud above the substrate and re-deposit in an uneven pattern on the substrate, if the cloud is not evacuated from the enclosure. Typically, therefore, the enclosure is operated under negative pressure, and an exhaust is provided at the bottom of the basin for both the liquid and vapor discharges.
Sometimes, the liquid flying off the chuck may find its way to the underside of the substrate. This requires rinsing the underside of the substrate after the spin operation has been completed, taking extra time in the manufacturing process.
The deficiencies of the conventional spin-apply tools show that a need still exists for improvement. To overcome the shortcomings of the conventional devices, a new tool is needed and this tool is provided by the following invention.